Data processing systems, such as general purpose computers, often employ a graphical user interface which allows for the simultaneous presentation of multiple windows which can at least partially overlap each other on the screen of a display device. FIG. 1A shows art example of a graphical user interface on a screen of a display device; there are multiple overlapping windows, often presented by multiple applications, which are running concurrently on the data processing system. While the ability to have multiple windows open concurrently can provide a rich operating environment, thereby allowing a user to view and operate on windows from multiple applications, it can also create confusion and clutter in the graphical user interface.